This research project focuses on the following: 1. Establishment of secretion rates, blood levels, and urinary excretion rates of ADH and oxytocin in nonpregnant, pregnant, and toxemic women, and in parturients and pureperas. By this study it is intended to evaluate the role of neurohypophysial peptides in relation to water metabolism during pregnancy, onset and maintenance of labor, delivery, and lactation. 2. Elucidation of the role of the vasopressinase-oxytocinase system of pregnancy in regard to its interrelationship with function, metabolism transport of ADH and oxytocin. 3. Study the physiology of neurohypophysial hormones by use of animal models: (a) immunization of nonpregnant and pregnat rats and rabbits against ADH and oxytocin, and observing the consequences of selective endogenous depletion of the respective hormone, (b) uniting female inbred rats in parabiosis, with one parabiont being or becoming pregnant, to study the hormonal and neurohumoral effects of pregnancy on uterus and mammary gland of the nonpregnant parabiont; by this method it is hoped that more can be learned about the hormonal and neurohumoral occurrences involved with the onset and maintenance of labor, and with lactation.